The miRNAs, let-7b and let-7a, of AnSC-Exos-origin reduced CCL7 expression by fibroblasts, inhibited recruitment of monocyte-macrophages, leading to a reduction in M2 macrophage accumulation, and contributed to the alleviation of PF (Fig. 7). The gene discussed is CCL7; the disease is pemphigus foliaceus.